Tribological needs in Electric and hybrid electric vehicles

Introduction

Mobility has long been a game-changer for humanity which traces back to the ancient invention of wheels. However, the real revolution began in 1769 with Nicolas Joseph Cugnot’s steam-powered automobile which kicked off curiosity for fuel experimentation. Karl Benz’s gasoline-powered vehicle in 1885 marked a major leap that propelled global mobility forward. Despite their power, these engines fails with frictional losses, even with lubrication declining their efficiency. As automobile usage increased which also increased the concerns about the environmental impact of internal combustion engines’ emissions. By 1989, with emissions from these engines accounting for 50% of total emissions in Europe which led to introduction of standardized emission norms. This initially targeted cars with engines equal to or greater than 2000 cc, then gradually expanded to encompass smaller engine sizes. This led to the establishment of similar norms worldwide, such as India’s Bharat Stage (BS) standards, aligned with Euro 6b norms, and China’s CN (CN1, CN2, CN3) standards, now at CN6. Stringent emissions regulations, coupled with concerns over exhaust emissions and dependence on fossil fuels, prompted exploration into alternative solutions like biodiesel blends. While biodiesel reduced certain harmful emissions, it also increased carbon dioxide emissions that necessitated further research into alternative solutions.

What are Hybrid and Electric vehicles

This led to research on automobiles with alternative source of energy which gave rise to hybrid and electric vehicles. Hybrid Electric Vehicles (HEVs) combines the internal combustion engines with electric motors for propulsion. This was first introduced by engineer Ferdinand Porsche in 1899. Recent years have seen a surge in interest in optimizing hybrid configurations that aims to maximize the efficiency of electric motors. Electric vehicles (EVs) offer enhanced efficiency compared to Internal Combustion Engine Vehicles (ICEVs), with potential efficiency levels around 85%, several times greater than ICEVs. This efficiency boost has led global automobile researchers and companies to shift focus towards EVs. EVs also boast advantages such as low noise operation, compact size, and lower weight compared to ICEVs. These vehicles are powered by batteries and fuel cells, representing a promising alternative in the pursuit of greener transportation solutions.

Fig-1 Future prediction in increased electric vehicle surge [2]

Need for improvement

EVs are comprised of several key components including motors, batteries, battery management systems, advanced driver assistance systems, sensors, and actuators. Despite their potential as a replacement for ICEVs, EVs face challenges such as high component costs and significant magnetic and electric losses. To address these drawbacks while capitalizing on the advantages of both EVs and ICEVs, HEVs emerged as precursors to pure EVs. Manufacturers of HEVs and EVs must face issues with increased electric and magnetic losses, alongside frictional losses, which can substantially impact efficiency and vehicle performance. To mitigate these losses, improvements in tribology the study of friction, wear, and lubrication are essential. Friction and wear prediction within vehicles is critical, as over 41% of losses are attributed to friction. Reduction of wear and enhanced lubrication capabilities not only extend component life but also significantly reduce costs. Lots of research underscores the importance of accurately calculating costs associated with tribological losses, emphasizing the potential for cost reduction through friction reduction strategies.

Fig-2 Schematic representation showing the complexities in electric vehicles [3]

Reference

[1] Hemanth, G. and Suresha, B., 2021. Hybrid and electric vehicle tribology: a review. Surface Topography: Metrology and Properties, 9(4), p.043001.

[2] https://auto.economictimes.indiatimes.com/news/industry/auto-oems-to-invest-usd-515-bn-on-ev-related-tech-upgrades-report/91735802

[3] https://readingagency.org.uk/Growing-popularity-of-EVs-could-see-spike-in-catastrophic-7249817.html